In many situations, it is desirable to encrypt communications sent over a network. For example, various government regulations, such as Health Insurance Portability and Accountability Act (HIPAA), Gramm-Leach-Bliley Act (GLBA), and Payment Card Industry Data Security Standard (PCI DSS), require the use of encryption, even on private networks. Such regulations can be satisfied by configuring network devices, such as routers, to encrypt messages received from client machines before transmitting those messages over the network. Receiving network devices then decrypt the transmitted messages before passing the messages to the recipient client machines.
In order for the network devices to be able to successfully encrypt and decrypt messages, all of the network devices participating in the encryption scheme need to use the same encryption keys and policies. A special network device can act as a key server, which distributes encryption keys and policies to all of the participating network devices. The key server can routinely update the keys and policies in order to provide increased security.
In some circumstances, a participating network device may not receive the new keys and policies distributed by the key server. For example, transient network errors may prevent the network device from receiving a policy update. As a result, that network device will no longer be able to successfully participate in the encryption scheme, since that network device will be using outdated keys and/or policies. In an attempt to prevent this scenario, key servers are often configured to retransmit policy updates to participating network devices that fail to acknowledge policy updates. Unfortunately, this solution does not scale well as the number of participating network devices increases, since the key server may effectively be overwhelmed by acknowledgments.
While the invention is susceptible to various modifications and alternative forms, specific embodiments of the invention are provided as examples in the drawings and detailed description. It should be understood that the drawings and detailed description are not intended to limit the invention to the particular form disclosed. Instead, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.